| 1. |
- Kindgren, Peter, et al.
(författare)
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Interplay between HEAT SHOCK PROTEIN 90 and HY5 Controls PhANG expression in response to the GUN5 Plastid Signal
- 2012
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Ingår i: Molecular Plant. - : Oxford University Press. - 1674-2052 .- 1752-9867. ; 5:4, s. 901-913
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Tidskriftsartikel (refereegranskat)abstract
- The presence of genes encoding organellar proteins in different cellular compartments necessitates a tight coordination of expression by the different genomes of the eukaryotic cell. This coordination of gene expression is achieved by organelle-to-nucleus or retrograde communication. Stress-induced perturbations of the tetrapyrrole pathway trigger large changes in nuclear gene expression in plants. Recently, we identified HSP90 proteins as ligands of the putative plastid signal Mg-ProtoIX. In order to investigate whether the interaction between HSP90 and Mg-ProtoIX is biologically relevant, we produced transgenic lines with reduced levels of cytosolic HSP90 in wild-type and gun5 backgrounds. Our work reveals that HSP90 proteins respond to the tetrapyrrole-mediated plastid signal to control expression of photosynthesis-associated nuclear genes (PhANG) during the response to oxidative stress. We also show that the hy5 mutant is insensitive to tetrapyrrole accumulation and that Mg-ProtoIX, cytosolic HSP90, and HY5 are all part of the same signaling pathway. These findings suggest that a regulatory complex controlling gene expression that includes HSP90 proteins and a transcription factor that is modified by tetrapyrroles in response to changes in the environment is evolutionarily conserved between yeast and plants.
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| 2. |
- Norén, Annelie
(författare)
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Äta sand och dricka vattenpöl är aja baja
- 2013
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Ingår i: Nerikes Allehanda. - Örebro : Nerikes Allehanda. - 1103-971X. ; :3/10, s. 22-22
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Höstrusk och dagissmittor ligger i startgroparna. Men hur snuskiga är egentligen barn? Blir man jättesjuk av att äta en snorkråka eller ta en slurk ur en vattenpöl?
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| 3. |
- Norén, Louise, et al.
(författare)
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Circadian and Plastid Signaling Pathways Are Integrated to Ensure Correct Expression of the CBF and COR Genes during Photoperiodic Growth
- 2016
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 171:2, s. 1392-1406
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Tidskriftsartikel (refereegranskat)abstract
- The circadian clock synchronizes a wide range of biological processes with the day/night cycle, and correct circadian regulation is essential for photosynthetic activity and plant growth. We describe here a mechanism where a plastid signal converges with the circadian clock to fine-tune the regulation of nuclear gene expression in Arabidopsis (Arabidopsis thaliana). Diurnal oscillations of tetrapyrrole levels in the chloroplasts contribute to the regulation of the nucleus-encoded transcription factors C-REPEAT BINDING FACTORS (CBFs). The plastid signal triggered by tetrapyrrole accumulation inhibits the activity of cytosolic HEAT SHOCK PROTEIN90 and, as a consequence, the maturation and stability of the clock component ZEITLUPE (ZTL). ZTL negatively regulates the transcription factor LONG HYPOCOTYL5 (HY5) and PSEUDO-RESPONSE REGULATOR5 (PRR5). Thus, low levels of ZTL result in a HY5- and PRR5-mediated repression of CBF3 and PRR5-mediated repression of CBF1 and CBF2 expression. The plastid signal thereby contributes to the rhythm of CBF expression and the downstream COLD RESPONSIVE expression during day/night cycles. These findings provide insight into how plastid signals converge with, and impact upon, the activity of well-defined clock components involved in circadian regulation.
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| 4. |
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| 5. |
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| 6. |
- Norén Lindbäck, Louise, et al.
(författare)
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An interplay between bZIP16, bZIP68, and GBF1 regulates nuclear photosynthetic genes during photomorphogenesis in Arabidopsis
- 2023
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Ingår i: New Phytologist. - : John Wiley & Sons. - 0028-646X .- 1469-8137. ; 240:3, s. 1082-1096
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Tidskriftsartikel (refereegranskat)abstract
- The development of a seedling into a photosynthetically active plant is a crucial process. Despite its importance, we do not fully understand the regulatory mechanisms behind the establishment of functional chloroplasts. We herein provide new insight into the early light response by identifying the function of three basic region/leucine zipper (bZIP) transcription factors: bZIP16, bZIP68, and GBF1. These proteins are involved in the regulation of key components required for the establishment of photosynthetically active chloroplasts. The activity of these bZIPs is dependent on the redox status of a conserved cysteine residue, which provides a mechanism to finetune light-responsive gene expression. The blue light cryptochrome (CRY) photoreceptors provide one of the major light-signaling pathways, and bZIP target genes overlap with one-third of CRY-regulated genes with an enrichment for photosynthesis/chloroplast-associated genes. bZIP16, bZIP68, and GBF1 were demonstrated as novel interaction partners of CRY1. The interaction between CRY1 and bZIP16 was stimulated by blue light. Furthermore, we demonstrate a genetic link between the bZIP proteins and cryptochromes as the cry1cry2 mutant is epistatic to the cry1cry2bzip16bzip68gbf1 mutant. bZIP16, bZIP68, and GBF1 regulate a subset of photosynthesis associated genes in response to blue light critical for a proper greening process in Arabidopsis.
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| 7. |
- Norén Lindbäck, Louise, 1984-
(författare)
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Coordination of two different genomes in response to light and stress
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- About 1.5 billion years ago, a photosynthetic bacteria was engulfed by a eukaryotic cell which initiated a symbiotic relationship and the evolution of the chloroplast as we know it today. The chloroplast has retained its own genome encoding for a number of proteins required for the function of the chloroplast. However, during the evolution most genes were transferred to the nucleus and the chloroplast is thus dependent on the nucleus to provide the majority of proteins necessary for its function. The distribution of genes encoding plastid proteins between two different cellular compartments requires a tight communication in order to coordinate gene expression during different growth conditions. The focus of my PhD studies has been to elucidate signalling pathways between the chloroplast and nucleus that enables the coordination of these two genomes in response to light and stress. The results in this thesis demonstrate that chloroplast retrograde signals triggered by changes in tetrapyrrole levels are important both in response to day-night cycles and during the response to stress. We identified a cytosolic regulatory complex and a novel mechanism that could explain how the tetrapyrrole-mediated signal can be transduced from the plastid to the nucleus and regulate nuclear gene expression in response to changes in the environment. My work further demonstrates that the tetrapyrrole-triggered plastid signalling pathway integrates with the circadian clock in order to fine-tune nuclear gene expression during photoperiodic conditions. These findings provide novel insight into how clock components and plastid signals converge in order to obtain the proper output. I have also examined the regulation of nuclear gene expression in response to redox and early-light signals by identifying transcription factors responding to these signals. My work demonstrates a novel mechanism by which redox-regulation of specific transcription factors directly links cellular redox status to gene regulation. The identified transcription factors were further shown to regulate nuclear genes encoding plastid proteins and they are of particular importance for anterograde control during the early light response and establishment of photomorphogenic growth.
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| 8. |
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| 9. |
- Pilheden, Mattias, et al.
(författare)
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Duplex sequencing uncovers recurrent low-frequency cancer-associated mutations in infant and childhood KMT2A-rearranged acute leukemia
- 2022
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Ingår i: HemaSphere. - : Wolters Kluwer. - 2572-9241. ; 6:10
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Tidskriftsartikel (refereegranskat)abstract
- Infant acute lymphoblastic leukemia (ALL) with KMT2A-gene rearrangements (KMT2A-r) have few mutations and a poor prognosis. To uncover mutations that are below the detection of standard next-generation sequencing (NGS), a combination of targeted duplex sequencing and NGS was applied on 20 infants and 7 children with KMT2A-r ALL, 5 longitudinal and 6 paired relapse samples. Of identified nonsynonymous mutations, 87 had been previously implicated in cancer and targeted genes recurrently altered in KMT2A-r leukemia and included mutations in KRAS, NRAS, FLT3, TP53, PIK3CA, PAX5, PIK3R1, and PTPN11, with infants having fewer such mutations. Of identified cancer-associated mutations, 62% were below the resolution of standard NGS. Only 33 of 87 mutations exceeded 2% of cellular prevalence and most-targeted PI3K/RAS genes (31/33) and typically KRAS/NRAS. Five patients only had low-frequency PI3K/RAS mutations without a higher-frequency signaling mutation. Further, drug-resistant clones with FLT3D835H or NRASG13D/G12S mutations that comprised only 0.06% to 0.34% of diagnostic cells, expanded at relapse. Finally, in longitudinal samples, the relapse clone persisted as a minor subclone from diagnosis and through treatment before expanding during the last month of disease. Together, we demonstrate that infant and childhood KMT2A-r ALL harbor low-frequency cancer-associated mutations, implying a vast subclonal genetic landscape.
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| 10. |
- Rixon Fuchs, Louise, et al.
(författare)
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GAN-enhanced simulated sonar images for deep learning based detection and classification
- 2022
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Ingår i: OCEANS 2022. - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- Data sparsity is a well-known limitation in the sonar domain. This limitation is a problem when applying data-intensive techniques from the computer vision community, such as deep learning models for detection and classification. One way of extending a sonar dataset is to use simulated sonar images however, these often have the drawback of looking non-realistic when compared to domain data. To overcome the data-sparsity problem as well as for generating realistic-looking sonar images, we introduce a pipeline where the possibilities and limitations of applying cycleGAN to enhance simulated forward-looking sonar images are explored. The results show improved classification performance when training a classifier on enhanced-simulated images compared to training on solely simulated images.
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